Brain Entropy: Linking Brain Structure to Task Activation.

Understanding how the brain's complex and diverse functions emerge from its structure has long been a central goal of neuroscience. Entropy, a measure of system irregularity, has become a powerful tool for quantifying the dynamics of brain activity. While previous fMRI-based brain entropy (BEN) studies have established its relationships with brain morphology (e.g., gray matter volume, GMV) and task activation, the pathway from structure to function remains incompletely understood. Specifically, it is unclear whether controlling for brain morphology (GMV) significantly alters the observed BEN-task activation relationship. In this study, we first replicated key prior findings, including the effects of sex and age on BEN and GMV, their spatial and brain-wide voxel-wise correlations, and the relationship between BEN and task activation across social cognition, reward, and emotion tasks. Subsequently, we examined the correlation between GMV and task activation, as well as the correlation between BEN and task activation after controlling for GMV. Our results successfully replicated previous findings. Crucially, the relationship between BEN and task activation remained largely unchanged after controlling for GMV. This indicates that BEN captures unique variance in task activation beyond what is explained by GMV alone, establishing BEN as a functional bridge linking brain structure to task activation. Future work should employ predictive analyses to quantify the added value of BEN in predicting task activation from structural information.